I've often used the analogy of occupations or jobs when thinking of niches. Some may say it lacks rigor or that it smacks of anthropomorphism, but it seems to fit well with most of the points raised in this discussion.
Sometimes we equip ourselves for a particular occupation that has already been defined and appears to offer satisfaction and rewards -- we occupy a pre-existing "niche" (think of professors and plumbers, or a returning migratory bird). If we're a more adventuresome type we may create a new occupation or career based on our particular talents and interests -- we create our own "niche" (think of the Google entrepreneurs or a strongly allelopathic invasive plant -- no parallels intended). Certainly we won't do very well if we choose a pre-existing career path that is already filled with persons more capable than we are -- the system has already filled that "niche" (think of trades and professions that limit entry by using sliding-scale qualification tests, or think of a diverse, complex and stable ecosystem). Nor will we do well if we try to create a new career for which there is no need or demand -- there is no such "niche" available within the system (think of door-to-door used toothbrush sales, or an ostrich in the tundra). Warren W. Aney Tigard, Oregon -----Original Message----- From: Ecological Society of America: grants, jobs, news [mailto:[EMAIL PROTECTED] Behalf Of Graham Smith Sent: Saturday, November 24, 2007 12:02 AM To: [email protected] Subject: Re: "unoccupied" niches and 'competitive exclusion" My view of a niche is similar, except I imagine them in terms of jobs =20= or occupations needed to fill a particular role in the environment. =20 For example "someone" needs to clear up dead animals, but the job =20 description (or niche description) will be variable in terms of =20 habitat, part of the animal needing broken down etc. Or a slightly different example would be weasels and stoats in the =20 British Isles where there is obviously a niche (or job) for a small =20 long bodied predator. In the UK this is filled by stoats and weasel, =20 but in Ireland it is filled only by stoats. But the stoats in Ireland =20= have a wider range of body sizes that cover roughly the same size =20 range covered by the two species in the UK. So in the Ireland =20 circumstances have created a niche filled by one species where the UK =20= two niches have evolved. Maybe too simplistic and anthropomorphic for many, but I find it =20 useful as an initial concept when students are struggling with the =20 idea of niche and seem to think its another name for a habitat or a =20 physical place. Graham Graham Smith [EMAIL PROTECTED] On 24 Nov 2007, at 04:11, Osmar Luiz Jr wrote: > Well, I usually don't think in the niche as some sort of "entity" =20 > like some > people do. > > > > In my vision, the niche is a set of opportunities that an organism =20 > is able > to explore. It can be constrained in part by the conditions offered =20= > by the > environment and part by the phylogenetic restrictions of the organism. > > In this way, the niche in neither pre-defined by the environment or =20= > by the > organism, but by a conjunction of both. > > > > Of course, we have a lot of examples of convergent evolution in quite > non-related taxons that lead us to assume some defined particular =20 > condition > driven speciation, but by the other hand there are examples of mass > extinctions of entire clades that could not adapt its morphologies =20 > to new > environmental conditions. Determine when one factor is more =20 > important than > other is a way to assume this dual facet of the niche and may =20 > render better > conclusions than keep trying to find rigid theoretical definitions. > > > > apologizes for the english > > > > Osmar Luiz Jr. > > Brazil > > > > > > > > ----- Original Message ----- > From: "Warren W. Aney" <[EMAIL PROTECTED]> > To: <[email protected]> > Sent: Friday, November 23, 2007 4:18 PM > Subject: Re: "unoccupied" niches and 'competitive exclusion" > > >> Does the species define the niche? Or (in evolutionary terms) does =20= >> the >> niche >> define the species? David seems to be saying that the species =20 >> defines the >> niche and Bill seems to be arguing that the niche exists =20 >> independent of >> the >> species filling it. Did Darwin's Galapagos finches evolve to fit >> pre-existing niches, or did they define the niche as they evolved? >> >> Warren W. Aney >> Tigard, Oregon >> >> -----Original Message----- >> From: Ecological Society of America: grants, jobs, news >> [mailto:[EMAIL PROTECTED] Behalf Of William Silvert >> Sent: Friday, November 23, 2007 1:31 AM >> To: [email protected] >> Subject: Re: "unoccupied" niches and 'coppetitive exclusion" >> >> >> This is how Hutchinson defined it, and his disciples have blocked any >> attempt to generalise the term, but many of us feel that a more =20 >> general >> definition is more useful. For example, if a species becomes =20 >> extinct, does >> its niche vanish with it? Since generally something will replace =20 >> it, it >> makes sense to describe the displacing species as moving into a =20 >> vacant >> niche. >> >> Of course the new species may have a somewhat different niche, but =20= >> I think >> of a niche as similar to an apartment -- new occupants my move the =20= >> walls >> and >> make some changes, but basically they occupy the same space. >> >> Unfortunately any attempt to generalise the niche concept runs =20 >> into the >> philosophy that definitions should never change. I have written =20 >> about the >> niche as a fuzzy set for example (which is basically what you see =20 >> in any >> book on niche packing even though they don't use the word), but since >> Hutchinson didn't use the word fuzzy, the concept is verboten. >> >> Bill Silvert >> >> >> ----- Original Message ----- >> From: "David Hilmy" <[EMAIL PROTECTED]> >> To: <[email protected]> >> Sent: Friday, November 23, 2007 4:25 AM >> Subject: Re: "unoccupied" niches and 'coppetitive exclusion" >> >> >>> The concept of =3D93niche=3D94 is very much defined around a = specific =3D >>> species- the >>> term itself is something of a misnomer in ecological terms =20 >>> because we =3D >>> assume >>> the traditional noun to describe a physical space or an element of =3D= >>> habitat, >>> or in the argument of some posted here, a set of >>> habitat/ecosystem/geographical parameters that are independent of =20= >>> the >>> species itself as though somehow =3D93vacant=3D94, yet the term as I = =20 >>> have =3D >>> always >>> understood it to be refers more accurately to the way in which a =3D >>> particular >>> organism fits into the ecosystem... >> >> Esta mensagem foi verificada pelo E-mail Protegido Terra. >> Scan engine: McAfee VirusScan / Atualizado em 23/11/2007 / Vers=E3o: >> 5.1.00/5170 >> Proteja o seu e-mail Terra: http://mail.terra.com.br/ >> >> >> >> --=20 >> No virus found in this incoming message. >> Checked by AVG Free Edition. >> Version: 7.5.503 / Virus Database: 269.16.4/1147 - Release Date: >> 23/11/2007 09:19 >> >>
